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Split Image Alignment

 
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crawdad



Joined: 22 Jun 2001
Posts: 16
Location: Heart of Georgia

PostPosted: Tue Jun 26, 2001 1:47 am    Post subject: Reply with quote

When I focus my Crown with the top mounted Graphic Rangefinder, the split images come together one on top of the other, i.e., one is higher than the other. They are not even or at the same height with each other. This can make it difficult to focus in some situations as it is hard to tell when the two images are perfectly aligned. Is this normal for the top mounted rangefinder, or should both images be at the same height and come together as "one" image rather than one on top of the other? Is there a way to adjust the height of the split images so that both are on the same level?
Thanks for any help.

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Ron
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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Tue Jun 26, 2001 2:54 am    Post subject: Reply with quote

the term Kalart used in their instructions is coincident, that is the images lay on top of each other and become one. I can't give you specifics, but if you remove the top (two screws) and look around you should see a screw that will adjust the tilt of one of the mirrors. a small amount will go a long way.

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crawdad



Joined: 22 Jun 2001
Posts: 16
Location: Heart of Georgia

PostPosted: Tue Jun 26, 2001 3:46 am    Post subject: Reply with quote

Les, you're right on the money again. There is a small screw right next to the right side mirror (as viewed from behind the camera). It only took a fraction of a turn to bring the two images into alignment. (A clockwise turn of the screw will bring the upper image down).
While I'm nagging everyone, could you possibly help me with one other woe I'm having with this rangefinder. When I use the light and bring the two images of the filament together, the distance scale indicates something totally different than if I didn't use the light. For example, I focused on a measured point 15' away without the use of the light and the rangefinder was right on. When I used the light, however, I had to rack it back to around 50' to get the two images of the filament to come together. Any ideas for the discrepancy and how to correct it? Any more secret screws anywhere?
As usual, I do appreciate your help. I hope others can benefit from this info as much as I.


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LelandRay



Joined: 24 May 2001
Posts: 115
Location: Mississippi

PostPosted: Tue Jun 26, 2001 12:32 pm    Post subject: Reply with quote

BOING! Time to file another bit of useful information. My Speed has the same alignment problem, and while it's not bad enough to keep me from focusing, it does slow down the process by a few seconds. Now where did I leave that screwdriver?

Ten minutes later... it's fixed.

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[ This Message was edited by: LelandRay on 2001-06-26 05:43 ]
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Henry



Joined: 09 May 2001
Posts: 1426
Location: Allentown, Pennsylvania

PostPosted: Wed Jun 27, 2001 4:45 pm    Post subject: Reply with quote

As I recall, there's another screw-adjustment inside the Kalart for the side-to-side coincidence of the images. It's a tricky adjustment to get just right (at least it was for me), but irritating as heck when it's out. But at least it doesn't require sighting in on objects at measured distances!
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Philip



Joined: 22 May 2001
Posts: 11
Location: Philadelphia, Pennsylvania

PostPosted: Wed Jun 27, 2001 6:11 pm    Post subject: Reply with quote

Ron,
I like to fool around with rangefinder devices & tinkering with my Kalart, got the miages totally coincident. Then, I sacrificed a mid 1970's broken minolta RF and re-mirrored the thing (yeah, it's not OEM, but this is definitely a USER camera) You're talking about a problem with the focus-spot right? It seems that the alignment on that little light & the beam that it's emitting is just as critical, or maybe your mirror needs to be re-silvered. In an earlier post, I mentioned a few questions I had about this method of focusing & figured that I have plenty of friends who work on precision (& not so precision) laser rangefinders, so I'm gonna have a few of them fool around with attaching a pocket laser pointer to the RF & rigging up a little chunk of aluminum for proper calibration. Too bad this is a Navy base & they frown on the use of those little pointers...
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crawdad



Joined: 22 Jun 2001
Posts: 16
Location: Heart of Georgia

PostPosted: Wed Jun 27, 2001 7:25 pm    Post subject: Reply with quote

Hi Phillip,
I'm not sure of the correct terminology on a lot of this stuff, so I'm not sure if it's called the "focus spot". What I'm talking about is the light inside of the rangefinder itself. When you press the little red button on the side of the rangefinder, a light goes on inside to assist in night time focusing. The light beam is split and the camera is suppose to be in focus when the two beams come together. The trouble I'm having is that when I use the rangefinder without the aid of the light, I get one focus point(a correct one), and when I use the light and focus until the two beams come together, the focus is way off. I was wondering if there were some way of calibrating the light so that it read the same focus point as when I focused without it. Am I making sense here? Sometimes I confuse myself.
Thanks much.

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Philip



Joined: 22 May 2001
Posts: 11
Location: Philadelphia, Pennsylvania

PostPosted: Thu Jun 28, 2001 1:35 am    Post subject: Reply with quote

Ah, top mounted RF. I'm used to fooling around with a Kalart & have gotten a hang of it enough that I can have it adjusted right within a half hour if I really wanted to change focus with lenses. It seems like the position of the light itself would be off inside the RF housing. Tha Kalart is a little simpler in that the focus assist light is an accessory that attaches to a hole on top of the RF housing. But it seems to me if the beam of the light is off kilter just like if the mirror is off, the focus will be off.
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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Thu Jun 28, 2001 2:51 am    Post subject: Reply with quote

For example, I focused on a measured
point 15' away without the use of the light and the rangefinder was right on.
When I used the light, however, I had to rack it back to around 50' to get the two images of
the filament to come together.

So far I haven't chimed in on this, cause I don't have a clue!
From my highschool physics the theory behind the rangefinder is that when you look through the hole part of the image you see gets deflected by a partial mirror to a rotating hard mirror (what the cam moves).

Notice if you move your eye back away from the camera, the double image stays put.

The light bulb in the focospot by Kalart and by Graflex is the same as your eye, it's just useing the other side of that partially silvered mirror.

The only thing that keeps the images (for your eye) and the filiments (focospot) apart is the position of that movable mirror, and when one is coincident the the other has to be.

This statement has to be true in order for the focospot to work and yet you have proven it to be false!


The position of the bulb shouldn't make a difference, just like the position of your eye doesn't make a difference.

Is it possible the mirror is moving between looking at the rangefinder and using the bulb?

Have you checked the rangefind and focospot with the ground glass?

Is the rangefinder working/accurate with the current lens?

Hey I'm grasping at straws here.



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crawdad



Joined: 22 Jun 2001
Posts: 16
Location: Heart of Georgia

PostPosted: Thu Jun 28, 2001 9:35 am    Post subject: Reply with quote

Les, I don't think the mirror is moving any. I've checked the rangefinder against the groundglass and it is right on. When I check the focuspot against the groundglass,it is way off. The rangefinder is accurate with the current 135 lens I have on it. The beam of light from the bulb shines directly into a mirror (which is tight) and is reflected 90 degrees through a small round glass before it reaches the rangefinder mirrors. My next step is to tinker with that small round glass and see if it might be disturbing the light beam in some way. You think you're grasping at straws!
Thanks.

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Ron
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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Sat Jun 30, 2001 2:48 am    Post subject: Reply with quote

Okay I gave up and looked at my Crown repair manual. It does talk about the ability to focus the rangelite (so my theory is all wet) and even shows a tool to help you!

They just don't tell you HOW to use the tool, infact they don't mention it at all!

the tool is a piece of wood 3/8x7/16x 3* long with one end cut at 45 with a mirror stuck on it and the other end cut at 9 the first two dimentions are the wide sides as the two other sides are tapered but gives no dimentions.

I get the idea that you stick in the top where the other mirrors would go, but after that what?

More grasping at light beams

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